function nav(){
    doca('.xiaomishouji').onmouseover=function(){
      doca('.down-menu-wrapper').style.display='block'
    }
    doca('.xiaomishouji').onmouseout=function(){
      doca('.down-menu-wrapper').style.display='none'
     
    }
    doca('.hongmi').onmouseover=function(){
      doca('.hongmi .down-menu-wrapper').style.display='block'
    }
    doca('.hongmi').onmouseout=function(){
      doca('.hongmi .down-menu-wrapper').style.display='none'
    }
  doca('.television').onmouseover=function(){
    doca('.television .down-menu-wrapper').style.display='block'
  }
  doca('.television').onmouseout=function(){
    doca('.television .down-menu-wrapper').style.display='none'
  }
  doca('.notebook').onmouseover=function(){
    doca('.notebook .down-menu-wrapper').style.display='block'
  }
  doca('.notebook').onmouseout=function(){
    doca('.notebook .down-menu-wrapper').style.display='none'
  }
  doca('.flat').onmouseover=function(){
    doca('.flat .down-menu-wrapper').style.display='block'
  }
  doca('.flat').onmouseout=function(){
    doca('.flat .down-menu-wrapper').style.display='none'
  }
  doca('.hea').onmouseover=function(){
    doca('.hea .down-menu-wrapper').style.display='block'
  }
  doca('.hea').onmouseout=function(){
    doca('.hea .down-menu-wrapper').style.display='none'
  }
  doca('.Router').onmouseover=function(){
    doca('.Router .down-menu-wrapper').style.display='block'
  }
  doca('.Router').onmouseout=function(){
    doca('.Router .down-menu-wrapper').style.display='none'
  }
  doca('.Hardware').onmouseover=function(){
    doca('.Hardware .down-menu-wrapper').style.display='block'
  }
  doca('.Hardware').onmouseout=function(){
    doca('.Hardware .down-menu-wrapper').style.display='none'
  }
  
  }
  nav();


// 吸顶
let xmNav=doca('.xm-nav')
window.onscroll =function(){
  let st =document.documentElement.scrollTop||document.body.scrollTop;
 
  if(st>=200){
    xmNav.style='position:fixed;top:0;width:100%';
    xmNav.style.transition='1s ease';
  }else{
    xmNav.style='position:static';
  }
}
  
  function doca (ele){
    return document.querySelector(ele)
}
function docall (ele){
    return document.querySelectorAll(ele)
   
}